1. Field of the Invention
The present invention relates generally to guardrail stanchions, guardrail systems and methods of affixing stanchions, and more specifically to stanchions, guardrail systems and methods for use on construction sites, and particularly to stanchions, guardrail systems and methods for use on concrete structures.
2. Background Information
Several guardrail devices are known that allow for safety protection at the edge of a construction, such as guardrails placed to prevent workers or objects from falling off the edge of a building under construction. Some form of protective barrier or guardrail is usually required around the edges of the workplace. Detailed regulations are established by various bodies designed to eliminate or reduce workplace hazards. Organizations such as the Occupational Safety and Health Administration (OSHA) in the United States and various state agencies, Workmen's Compensation Boards and trade organizations often require some form of barrier protection in the workplace. Even if OSHA or other regulatory bodies do not require such systems, or where requirements for barrier protection are lax or less stringent (such as may be the case from jurisdiction-to-jurisdiction or country-to-country), insurance companies would insist upon the best safety or provide incentives for use of best practices.
In the United States, OSHA has established construction standards for guarding open-sided floors and roofs, including erection of a “standard railing”, which comprises a top rail, intermediate rail, toeboard and posts, to enclose such open spaces. The top rail is required to have a vertical height of approximately 42 inches from the upper surface of the top rail to the floor, platform, runway or the like being protected. The intermediate rail is specified to be halfway between the top rail and the floor, etc., while the toeboard is required to be at least 4 inches in vertical height from its top edge to the level of the floor, platform, etc. In addition, the toeboard must be securely fastened in place and must be flush with the floor such that not more than a ¼-inch clearance exists between the toeboard and the floor. An assembly so constructed is sometimes referred to as a “standard railing”.
Various attempts have been made to provide construction guardrail systems, some of which may or may not be considered “standard railings”. One such guardrail system involves use of a support stanchion as shown in U.S. Pat. No. 4,015,827 issued to Brand on Apr. 5, 1977, for supporting a life line around the perimeter of an elevated area such as a building roof. The stanchion is anchored to the roof or building support by bolts or screws embedded into the floor. Another system includes use of a support as shown in U.S. Pat. No. 5,560,588, issued to Hilliard, for a temporary guard railing erected along the edges of open floors, balconies, stairs, and the like in a building under construction. This device is secured to the floor surface by running screws or other male connectors through the support and into the floor surface. Connecting devices to the floor of a structure, such as by nailing a standard or stanchion to a concrete floor results in damage to the floor, often requiring expensive or time-consuming repair, among other problems.
Further safety railing systems or stanchions for concrete slab walls are shown in U.S. Pat. No. 5,377,958 to Palmer, and U.S. Pat. No. 6,547,223 to Letourneau. The device in Palmer involves vertically extending stanchion members mounted to wall brackets, which the brackets in turn are mounted below the exterior facia of the wall by fasteners driven through the brackets into the underlying wall structure. The device in Letourneau involves a railing that engages in a cavity of an anchor where the anchor is rigidly mounted into the concrete wall panel at a face or end of the floor slab. Here again, such systems have fasteners that are driven into or imbedded within the concrete or floor structure. These systems also cover an edge area of the flooring which must be removed in order finish the edge or the areas adjacent the edge.
A further system as shown in U.S. Pat. No. 6,270,057 issued to Highley et al., involves a system for use on a structure where concrete is poured upon corrugated material. The reusable multi-story building construction guardrail system includes a bar element bolted to an outside of a frame member that forms the outer perimeter of a conventional elevated slab floor support structure consisting of I-beam floor joists and trusses that serve to support horizontal floor supports and the corrugated floorplan thereabove onto which concrete is poured in order to form an elevated concrete slab floor surface in a multi-story building. The protection system is bolted directly to the perimeter frame member or support structure upon which the concrete is poured. Yet a further system as shown in U.S. Pat. No. 4,909,483 to van Herpen involves a handrail support which is kept in place by a weight element placed upon a base. The simplicity and usefulness of the present invention in this application is neither taught nor suggested by these mechanisms.
A number of guard rail mechanisms for which patents have been granted, also relate to the slab-grabber or clamping variety. Some examples of such devices are found in U.S. Pat. No. 4,669,577 to Werner; U.S. Pat. No. 3,995,834 to Melfi; U.S. Pat. No. 3,881,698 to Marsh; U.S. Pat. No. 3,863,900 to Dagiel et al.; and, U.S. Pat. No. 7,234,689 to Kuenzel. These devices are typically clamped to the edge of a slab of the construction. They generally mimic a C-clamp mechanism which compresses upon the top and bottom sides of a slab, while also covering an edge portion of the slab to which the clamp is attached. While the clamping action avoids damage to the floor element, being that it is attached at the edge necessarily requires a subsequent movement of the device in order to work on the structure at that edge of the slab. The simplicity, reliability and usefulness of the present invention in this application in not taught nor suggested by these slab grabber mechanisms.
Various other mechanisms for which patents have been granted relate to other types of compression-fit or friction-fit mechanisms. An example of such device is found in U.S. Pat. No. 3,662,993 to Lionetto. In such application, posts span from the floor to ceiling and are fastened into position with jacks or threaded bars. While such mechanisms generally avoid direct damage to the floor or structure, and also avoid placement or coverage over the edge of the slab, the reliability of such compression-fit mechanisms is questioned. Natural or unnatural changes, such as expansion or contraction of the structure materials, present concern due to slippage of the devices from a secured safety position within the bay of the structure. Similar expansion or contraction or other changes to the device itself may also occur. The material used for the device is different than the concrete or other material that is used for the structure, and the expansion and contraction characteristics are different such that the materials expand and/or contract at different rates. Such differences in the material characteristics of the device and structure present further variability issues for the stability of a compression-fit system. As the structure or device expands or contracts, the compression-fit forces are changed. The changed forces may cause the device to break, or to slip or weaken its fit against the structure, or if the device does not yield, in an extreme case the structure may shift or crack. In some instances a post is also used as (or has the effect of being used as) a shoring or re-shoring device. A shoring device is commonly understood to be a device which supports or holds the form or deck, as opposed to a re-shoring device which holds or supports the resulting concrete structure. In either case, the expansion of the device might lift the ceiling slightly, thereby causing other posts or shoring devices to loose their compression fit. In some cases the posts fall from position and are otherwise unworkable as a safety device. In sum, the compression-fit devices having a post span from floor to ceiling are inherently suspect and unworkable for use in a safety role. By the same token, compression-fit posts that span from wall-to-wall are also unworkable.
Other friction-fit mechanisms for which patents have been granted include U.S. Pat. No. 3,589,682 to Dickey granted Jun. 29, 1971, and U.S. Pat. No. 3,439,898 to Cleveland et al granted Apr. 22, 1969. Dickey says that the general practice at the time in erection of such safety fences involved use of lengths of 2-by-4 lumber cut to approximately the spacing between the floor and ceiling, and wedged into place in any expedient manner. One or more horizontal rails were commonly nailed to such vertical pieces of lumber to construct a crude fence. In practice it was found that the wedging of such vertical pieces of lumber can never be made completely secure and the lumber will rapidly dry out, being exposed to very severe weathering, and will become loose and sometimes blow away altogether causing an additional hazard to persons standing below. The same thing can occur merely because the concrete itself dries out and will shrink very slightly thereby causing such vertical pieces of lumber to become loose and fall (or in other cases, cause the lumber to tighten or result in bowing or nail pulls). The appearance of the otherwise safe structure may cause a false sense of security, further exacerbating the hazard. Dickey uses a telescoping column for erection of a safety fence or guardrail at a building under construction. A manually operable jacking system is used for extending the column and forcing upper and lower pads firmly against the ceiling and floor of the building to hold the column firmly in position. Cleveland also shows a compression-fit safety barrier and barrier fence having telescoping columns. Such telescoping compression-fit systems may be positioned so as to not obstruct the edge of the flooring and may reduce the potential for direct damage to the structure (such as damage that might otherwise be caused by nailing). However, such systems lack the simplicity and reliability of the present invention. They also are subject to variables encountered with material expansion as noted above, and thus are suspect and unreliable for a safety role. Further, improvements are always desired in any art. Other drawbacks of such friction-fit mechanisms include the cost of having columns span from floor-to-ceiling or having expensive threaded components or other means for telescoping action. Precautions are also required to prevent screw-type mechanisms to not loosen, or such mechanisms may require a special tool such as a wrench or other tool to set-up or extend the apparatus for a friction fit. The size of the floor-to ceiling mechanisms are bulky and often troublesome to transport and/or store. Further, the over-tightening of a post or column may result in damage to the floor or ceiling and corresponding loosening of adjacent posts or columns. Such mechanisms are generally troublesome to set-up.
Disadvantageously, while the above and other past approaches may be sufficient in some respects for their particular purposes, each has deficiencies. Some of the approaches require a considerable effort in set-up and take-down; or still result in damage to the structure (such as by nailing, which commonly requires drilling or use of a hammerdrill or other aggressive tools) which in turn requires additional expense, delay and labor for correction; or connect adjacent to, or cover up, the edge of the structure thus requiring subsequent movement in order to work on or at the edge location; or rely on a compression or friction fit which is susceptible to slippage and other troubles as mentioned. Further, with such approaches there is an ever-present uncertainty as to whether the systems are indeed compliant with OSHA or other requirements, or if initially compliant, whether they can maintain compliance and be safe throughout the construction effort. Since the temporary safety mechanisms are typically repeatedly moved in order to undertake construction efforts, workers (and the owners of the structures) must be diligent in assuring that the systems continue to be safe. Even if some of the prior systems comprise a “standard railing” and/or guardrail system that securely connects to the structure without nailing or other damage to the structure, they are either of a compression-fit variety, or disadvantageously cover the edge location of the flooring.
The known guardrail devices are often complicated, expensive, typically result in damage to the structure to which they are affixed, are difficult to secure, and are susceptible to non-compliance with OSHA. Many are not reusable, many are limited to a particular site configuration, require temporary removal and re-setting when a forklift needs access, are in the way when working on an outside edge of the structure (such as when laying brick or pouring outside edge wall or constructing outside edge wall), require the subsequent patching of holes or damage to the structure or require rework of concrete that was damaged by a nail gun or drill or other anchor mechanism. A crew of workers is typically required to assemble guardrails (spending time and labor that could otherwise be devoted to working on the actual structure as opposed to a temporary safety system that will be obsolete upon completion of the construction.
While some of the known guardrail devices are connected to the edge of a concrete deck by friction or grabbing mechanisms, others are mounted into the deck or walls with bolts or nails (or use anchors that are affixed within the structure), or use weights to hold the guardrail adjacent an edge of the deck. Workers will erect one of the many known devices or systems (or cobble together a solution for a given customized fix) and deal with the follow-up or related tasks as needed. For instance, workers will patch holes that were created when nails or other fasteners were removed from the deck. Workers will move a railing from an edge so that the edge area may be cleared for finishing or treated with additional building materials. The railing may be temporarily removed to allow a fork lift to place materials on the deck, and then reassembled or nailed back into position. Workers may also take special care to not lean too hard against a rail held down by weights, or take care not to fasten a life-line to the guardrail, or to undertake one of many other tasks or precautions due to the nature of the known devices or systems.
Damages made to the walls of a structure have become increasingly problematic in recent years especially since owners of the structures sometimes prefer to keep the raw walls exposed to view for aesthetic purposes. Until somewhat recently, drilling into a wall to fasten a board or other safety mechanism was not considered a problem since the walls would typically be covered with paint or sheetrock or other materials. Drilling into the floor or walls or ceilings creates unsightly marks, and the repairs are often unsatisfactory. Further, with a preference for having exposed walls, an emphasis is often placed on positioning conduit within the walls. Thus, drilling into the walls becomes risky. Indeed, safety mechanisms are required to be used on a project, so the workers and owners often have to deal with the competing goals of safety vs. appearance and costs.